3D Printed K-Band Air-Filled Waveguide Directional Coupler Integrated with PCB Using a Through-Patch Transition

In this paper, a recently developed highly integrated hybrid fabricated stack-up is explored for the implementation of passive waveguide microwave front-end components such as power dividers/combiners. The stack-up leverages the additive manufacturing for integration of a 3D printed and metal-coated air-filled waveguide with a Printed Circuit Board (PCB) by sharing a common ground plane, which allows for further integration with active circuitry. A through-patch transition is used to interconnect the two guides. The concept was experimentally verified by fabrication and measurements of an exemplary equal power split directional coupler in WR-42 waveguide geometry to operate at f
0
= 20 GHz being fed by on-PCB microstrip lines.